High-speed automatic hydraulic pressing system

ABSTRACT

A high-speed automatic hydraulic pressing system which can effectuate a high-speed and high-pressure operation of pressing materials with an automatical repetition, employing a low-powered low-pressure oil pump. Said system comprises a low-pressure oil pump, an oil circuit for supplying oil to a pressing mechanism and an oil pressure intensifying mechanism which can work in synchronous therewith to generate a high-pressure oil. The flow of oil is switched over by a timer at an oil pressure direction changing valve provided on the oil circuit to act on the pressing mechanism and the intensifying mechanism to simultaneously restore a pressing piston and an intensifying piston to the starting position. Then, a pressure switch is urged to switch the direction changing value back to the starting neutral position to complete one cycle of operation. Thus the cycle being repeated automatically, the system according to the present invention can effectively and continuously press materials at high-speed.

United States Patent 1 3,691,946 Ando [4 1 Sept. 19, 1972 [54] HIGH-SPEED AUTOMATIC HYDRAULIC. PRESSING SYSTEM [72] Inventor: Shigeo Ando, No. 5-272, Suehirocho, Chosi, Japan [22] Filed: May 28, 1971 [21] Appl. No.: 147,787

[52] US. Cl. ..100/269 B, 72/453 [51] Int. Cl. ..B30b l/30 [58] Field of Search ..100/269 B; 72/453 [56] References Cited UNITED STATES PATENTS 1,054,194 2/1913 Gerdau ..100/269 B X 1,230,492 6/1917 Kristufek [.100/269 B X 2,403,912 7/1946 D011 ..100/269 B UX 2,657,429 11/1953 Faust 100/269 B UX 3,296,853 l/1967 Beche ..100/269 B X Primary Examiner-Robert L. Bleutge Attorney-Shlesinger, Fitzsimmons & Shlesinger [57] ABSTRACT A high-speed automatic hydraulic pressing system which can effectuate a high-speed and high-pressure operation of pressing materials with an automatical repetition, employing a low-powered low-pressure oil pump. Said system comprises a low-pressure oil pump, an oil circuit for supplying oil to a pressing mechanism and an oil pressure intensifying mechanism which can work in synchronous therewith to generate a highpressure oil. The flow of oil is switched over by a timer at an oil pressure direction changing valve provided 'on the oil circuit to act on the pressing mechanism and the intensifying mechanism to simultaneously restore a pressing piston and an intensifying piston to the starting position. Then, a pressure switch is urged to switch the direction changing value back to the starting neutral position to complete one cycle of operation. Thus the cycle being repeated automatically, the system according to the present invention can effectively and continuously press materials at high-speed.

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HIGH-SPEED AUTOMATIC HYDRAULIC PRESSING SYSTEM This invention relates to a high-speed automatic hydraulic pressing system and, more particularly, to a hydraulic pressing system which can effectuate a highspeed and high-pressure operationemployinga lowpressure pump of large capacity is required. Such'a conventional pressing machine, however, has defects that attention must be paid to anti-pressuremeasures at mechanical designing and that installation cost inevitably increases.

It is, therefore, an object of the present invention to provide a high-speed automatic hydraulic pressing system which can be actuated by a low-powered lowpressure pump by way of a pressing piston and a pressure intensifying piston and permits a constant repetition of the high-speed and high-pressure pressing operation by simultaneously restoring said pressing piston and intensifying piston thereby to terminate one cycle of the operation.

It is another object of the present invention to provide a high-speed automatic hydraulic pressing system which is simple in structure and high in efficiency and durability.

Essentially, according to the present invention, there is provided a high speed automatic hydraulic pressing system comprising a low-pressure oil pump for sucking oil from an oil tank; an oil circuitcommunicating said oil tank with a pressing mechanism and provided therebetween with a pressure control valve, an oil pressure direction changing valve, a valve with a counter- FIG. 1 is a diagrammatical sectionalview of an oil pressure circuit according to this invention showing the states of each section in the starting period of the operation; I a

FIG. 2 is a diagrammatical sectional view like FIG. 1 in the early period of the operation;

FIG. 3 is a diagrammatical sectional view like FIG. I in the pressure intensifying period;

FIG. 4 is a diagrammatical sectional view like FIG. 1 showing the states of each section in the period when a piston goes down after the pressing action; and

FIG. 5 is a diagrammatical sectional view like FIG. 1 showing the states of each section restored to the starting position at the termination of one cycle of the operation.

Referring now to the drawings, numeral 1 designates a low-pressure pump for sucking oil stocked in an oil tank 2 through a filter 3-andan oil suction pipe 4. The sucked up oil is introduced through a low-pressure oil pipe 5 to a pressing mechanism 6. Said oil pipe 5 is provided with a pressure control valve 7 for sequentially releasing oil in occasion of excessive pressure and an w oil pressure direction changing valve 8 operable by flow prevention valve, another counterflow prevention valve, a further counterflow prevention valve operable by a pilot pressure, a pressure switch and a flow control valve, said pressing mechanism including a larger cylinder holding a larger piston for pressing a material and a smaller cylinder formed coaxially in said larger piston and holding a smaller piston fixed to said larger cylinder; an oil pressure intensifying mechanism connected to said oil circuit through diverged feed pipes and a high-pressure oil pipe for forwarding high-pressure oil generated from said intensifying mechanism to said pressing mechanism to press the material more strongly, said intensifying mechanism including a larger cylinder holding a larger piston for intensifying the oil pressure and a smaller cylinder formed coaxially in said larger cylinder and holding a smaller piston fixedto.

said larger cylinder; a timer for switching over said direction changing valve after a fixed time to urge said flow control valve and said counterflow prevention valve operable by a pilot pressure thereby to cause simultaneous restoration of said larger pressing piston of the pressing mechanism and said larger intensifying piston of the intensifying mechanism, said simultaneous restoration exerting an elevated pressure on said pressure switch to switch back the direction changing valve to the starting neutral position, thereby automatically and rapidly repeating the cycle of the operation.

Various further and more specific objects, features and advantages of this invention will be made apparent from the following description taken in connection with the accompanying drawings in which:

electro-magnetism.

Said pressing mechanism 6 includes a larger cylinder 9 holding therein a larger piston 10 and a smaller cylinder 11 formed in said larger piston 10 in its axial direction and holding therein a smaller piston 12 fixed to said larger cylinder 9 as depicted in the drawings. In said smaller piston 12 is formed an oil supply bore 13 axially extending therethrough to open inside said smaller cylinder I]. Said oil supply bore 13 is connected to the low-pressure oil pipe 5. In the drawings, a cavity inside the larger cylinder 9 is devided by the vertically moving larger piston 10 in two chambers, a piston urging chamber R in its lower portion and a piston restoring chamber R in its upper portion.

Numeral l4 designates a pressure intensifying mechanism. Numeral 15 designates a feed pipe to said pressure intensifying mechanism 14 which is diverged from the low-pressure oil pipe 5 between the oil pressure direction changing valve 8 and the pressing mechanism 6. Said diverged feed pipe 15 is provided with a counterflow prevention valve 17 and a sequentially working valve 16 equipped with another counterflow prevention valve to release oil when it exceeds a fixed pressure.

The pressure intensifying mechanism 14 includes a larger cylinder 18 holding therein a larger pressure intensifying piston 19, and a smaller cylinder 20 formed coaxially in said larger piston l9 and holding therein a smaller piston 21 fixed to said larger cylinder 18. In said smaller piston 21 is formed an oil supply bore 22 axially extending therethrough to open inside said smaller cylinder 20. In the lower and upper portions inside the larger cylinder 18, there are formed a piston urging chamber R and a piston restoring chamber R To said piston urging chamber R is the feed pipe 15 connected, and there is provided a high-pressure oil pipe 23 connecting said oil supply bore 22 to the piston urging chamber R of the pressing mechanism 6.

Numeral 24 designates another oil pipe provided between the oil tank 2 and the piston urging chamber R Said oil pipe 24 is equipped with a counter-flow prevention valve 25 which permits a backward flow of oil when a pilot pressure iseffected pilot pressure oil pipe 26.

Numeral 27 designates an oil pipe Connecting the oil pressure direction changing valve 8 and the piston restoring chamber R, of the pressing mechanism 6. Said oil pipe 27 is accomodated with a pressure switch 28 which acts on the direction changing valve 8 to switch it back to the former state when the oil pressure exceeds the fixed degree. A feed pipe 29 to the chamber R of the intensifying mechanism 14 is diverged from said oil pipe 27 and accomodated with a flow control valve 30. I

thereon through a Numeral 31 designates a pressing board, 32 a pressure holding board and numeral 33 is a material to be pressed with the hydraulic pressing machine according to this invention.

An operation for pressing the material 33 with the present system is described as follows;

The low pressure pump 1 is actuated as shown in FIG. 1 and the oil pressure direction changing valve 8 is brought to its operative position to supply oil below a fixed pressure to the smaller cylinder 1 l of the pressing mechanism6. The oil supplied to said smaller cylinder ll rapidly thrusts up the larger piston and simultaneously, oil in the tank 2 flows into the chamber R of the larger cylinder 9 through the valve 25. When the larger piston 10 is pushed up as shown in FIG. 2 to press the material 33 between the boards 31 and 32, the oil pressure in the low-pressure oil pipe 5 resultantly increases to exceed the fixed limit and then to urge the valve 16 to release the oil.

As shown in FIG. 3, the oil is introduced to the chamber R of the pressure intensifying mechanism 14 and actuates the intensifying piston 19 to generate high pressure inside the smaller cylinder 20. The generated high pressure is constantly forwarded to the chamber l9 exerts a pressure on the pressure switch 28 to R of the pressing mechanism 6 through the high-presv sure oil pipe 23 to further effect on the material 33.

After lapse of a certain period under the above condition, the direction changing valve 8 is switched over by a timer or some other ordinary methods to forward flow of the oil in the chamber R, to the oil tank .2. Accordingly, the larger piston 10 goes downward and is restored to the starting position. At the same time, the

restore the oil pressure direction changing valve 8 to the starting neutral position thereby completing one cycle of operation. 1

What is claimed is:

1. A high speed automatic hydraulic pressing system comprising a low-pressure oil pump for sucking oil from an oil tank; an oil circuit communicating said oil tank with a pressing mechanism and provided therebetween with a pressure control valve, an oil pressure direction changing'valve,'a valve with a counterflow prevention valve, another counterflow prevention nected to said oil circuit through diverged feed pipes and a high-pressure oil pipe for forwarding high-pressure oil generated from said intensifying mechanism to said pressing mechanism to press the material more strongly, said intensifying mechanism including a larger cylinder holding a larger piston for intensifying the oil pressure and a smaller cylinder formed coaxially in said larger cylinder and holding a smaller piston fixed to said larger cylinder; a timer for switching over said direction changing valve after a fixed time to urge said flow control valve and said counterflow prevention valve operable by a pilot pressure thereby to cause simultaneous restoration of said larger pressing piston of the pressing mechanism and said larger intensifying piston of the intensifying mechanism, said simultaneous restoration exerting an elevated pressure on said pressure switch to switch back the direction changing valve to the starting neutral position, thereby automatically and rapidly repeating the cycle of the operation. 

1. A high speed automatic hydraulic pressing system comprising a low-pressure oil pump for sucking oil from an oil tank; an oil circuit communicating said oil tank with a pressing mechanism and provided therebetween with a pressure control valve, an oil pressure direction changing valve, a valve with a counterflow prevention valve, another counterflow prevention valve, a further counterflow prevention valve operable by a pilot pressure, a pressure switch and a flow control valve, said pressing mechanism including a larger cylinder holding a larger piston for pressing a material and a smaller cylinder formed coaxially in said larger piston and holding a smaller piston fixed to said larger cylinder; an oil pressure intensifying mechanism connectEd to said oil circuit through diverged feed pipes and a high-pressure oil pipe for forwarding high-pressure oil generated from said intensifying mechanism to said pressing mechanism to press the material more strongly, said intensifying mechanism including a larger cylinder holding a larger piston for intensifying the oil pressure and a smaller cylinder formed coaxially in said larger cylinder and holding a smaller piston fixed to said larger cylinder; a timer for switching over said direction changing valve after a fixed time to urge said flow control valve and said counterflow prevention valve operable by a pilot pressure thereby to cause simultaneous restoration of said larger pressing piston of the pressing mechanism and said larger intensifying piston of the intensifying mechanism, said simultaneous restoration exerting an elevated pressure on said pressure switch to switch back the direction changing valve to the starting neutral position, thereby automatically and rapidly repeating the cycle of the operation. 